1. Field of the Invention
The present application is directed to alignment systems in an image forming apparatus and particularly to systems that move a media sheet against a reference edge as the media sheet moves along a media path.
2. Description of the Related Art
Image forming apparatuses include a media path for moving media sheets from an input area, through a transfer area, and ultimately to an output area that is usually on an exterior of the apparatus. The media path may also include one or more nips formed between opposing rolls through which media sheets pass. The nips may function to drive the media sheets along the media path and/or to align the media sheets.
The media sheets should move along the media path in a consistent fashion. This is necessary to ensure the media sheets are located at the transfer area at the precise time to receive the images. The media sheets should also be aligned by the time they reach the transfer area. Proper alignment ensures the images are positioned at the correct location on the media sheets. A misaligned media sheet at the transfer area may result in a print defect as the image is not centered or otherwise located on the media sheet as desired.
In an image forming apparatus such as a multi-function printer, a post-processing device (finisher) is provided next to a paper discharge unit in the image forming apparatus body in order to carry out post-processing, such as hole punching and stapling, to a sheet on which an image has been formed.
In such a post-processing device, a sheet discharged from the image forming apparatus body may be aligned to a left or a right reference edge, or may be center-fed such that there may be a need to re-align the sheet discharged from the image forming apparatus depending on the location of the post-processing device (i.e. left to right, right to left, center-fed to right, center-fed to left). The amount of shift needed and the distance of travel before the media sheet reaches the post-processing device may pose challenges to the compactness of the design of the multi-function printer. Further, a sheet discharged from the image forming apparatus body may be skewed with respect to the media feed direction such that correction is necessary.
Therefore, there is a need to provide a media aligning mechanism to re-align and correct the skew of a media sheet discharged or to be discharged from an image forming apparatus body to effectively carry out a post-processing operation.